According to the suggested model, initial forms of polyphonic singing (proto-polyphony) were distributed in all ancient populations of Homo Erectus (or more correctly, archaic Homo Sapiens). This ancient tradition of polyphony singing, with the new human cognition and the ability to ask questions was taken along on the long journey to different regions of the world (349).
After the advent of articulated speech musical (pitch) language lost its initial survival value, was marginalized and started disappearing. Early human musical abilities started to decline. The ancient tradition of choral singing started disappearing century by century and millennia by millennia. Musical activity, formerly an important part of social activity, also started to decline and became a field for professional activity. As a result of this decline, in some regions of the world the tradition of vocal polyphony is almost completely lost (349).The reason why "[t]he tradition of choral polyphonic singing has been lost among East Asian and Australian Aboriginal populations [while] still strongly present in European, Polynesian, Melanesian, and particularly – sub-Saharan African - populations" is due to "the shift to articulated speech among different populations in different epochs. Regions where vocal polyphony is absent (lost) must have shifted to articulated speech earlier. Regions where the tradition of vocal polyphony is still alive and active must have shifted to articulated speech much later" (350). Thus, for Jordania, we find no trace of choral polyphony in East Asia or Australia because articulated speech must have developed at a much earlier period there than in Europe, Oceania and Africa, and the advantages conferred by such an ability would have made coordinated musical activity no longer necessary.
*Jordania's book was at one time freely available for Internet download, but that website has now disappeared. As I understand it, a new edition is currently in press and should be available for purchase soon.